Air flow control system

ABSTRACT

Environmental temperatures are controlled by selectively proportioning air flow from a pair of air flow paths by generation of a force proportional to temperature and dependent solely upon temperature for oppositely and proportionally changing registration of small openings in pairs of perforated plates laterally disposed in the air flow paths. A direct-acting, expandible-material, temperature-sensitive device is located adjacent those perforated plates and is used to generate that force; and a remote-control system permits the set point of that temperature-sensitive device to be adjusted.

O United States Patent 1 [111- 3,738,572 Hall, Jr. June 12, 1973 [54]AIR FLOW CONTROL SYSTEM 2,259,061 10/1941 Caffier 73/3628 Inventor:William K Hall J 4539 Bobbitt 3,235,178 2/1966 Mlles et a1. 236/13Dallas 75229 Primary Examiner-William E. Wayner [22] Filed: Dec. 30,1971 Attorney--Rey Eilers [21] Appl. No.: 214,350

7 B A Related US. Application Data [5 A STR CT [63] Continuatiomim an ofSer No 636 748 Ma 8 Envlronmental temperatures are controlled by selec-1967 Pat 3 tively proportioning air flow from a pair of air flowcontinuation-in-part of Ser. No. 577,298, Sept. 6, Paths y generationofa force Proportional to p 1966, abandone ture and dependent solelyupon temperature for oppositely and proportionally changing registrationof small [52] US. Cl. 236/49, 236/51 p g in pairs of p o ated plateslaterally disposed 51 Int. Cl F24f 11/00 in the air flow p Adirect-acting. xpan i le- 58 Field of Search 236/49, 13, 51; material,temperature-Sensitive device is located i 1 5 1 cent those perforatedplates and is used to generate that force; and a remote-control systempermits the set [56] Referen es Cit d point of thattemperature-sensitive device to be ad- UNITED STATES PATENTS Justed-922,783 5/1909 Korting 237/6 8 Claims, 25 Drawing Figures Patented June12, 1973 3,738,572

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AIR FLOW CONTROL SYSTEM Related Applications: This application is acontinuation-in-part of application Ser. No. 636,748, filed May 8, 1967,now U.S. Pat. No. 3,669,349 issued June 13, I972 which is acontinuation-in-part of application Ser. No. 577,298, filed Sept. 6,1966, now abandoned.

This invention relates to environmental control systems and moreparticularly to the control of air flow from warm and cool sources. In amore specific aspect, the invention relates to a flow control systemwhich includes pairs of relatively slidable perforated plates positionedtransversely of the flow paths leading from the sources. In a stillfurther aspect, the invention relates to the development and direct useof forces produced solely in response to change in temperature forvarying relative positions of such perforated plates.

Prior Art: A wide variety of systems has been heretofore employed in thedelivery of air to one or more zones where individual control of thetemperature for each zone is desired. In the past, heat exchange unitshave been supplied for each zone with temperature sensing means forcontrolling the heat supplied to, or extracted from, air flowing to suchzone. In air flow systems, mtor-driven mechanically-actuated dampershave been widely employed. Further, in high pressure systems, the flowof super-cooled air under high pressure to a particular area has beenemployed for inducing circulation.

The practical utilization of many of these previously developedtemperature control systems has been limited by several factors. Many ofthe prior systems have not only required complex and expensive controland actuation devices for each temperature control unit, but have oftenrequired a separate control unit for each zone for which temperaturecontrol is desired. In addi- 'tion to the economic limitations thusimposed upon many previously developed systems, the complexmotor-operated construction of some systems has often not been entirelysatisfactory with respect to maintenance requirements or operatingefficiency. Further, many of the systems previously employed for zonetemperature control have not been responsive to the temperature of airin the desired zone.

Summary: In accordance with the present invention, conduit means ismounted adjacent to a supply opening leading to a zone to be temperaturecontrolled. Structure is provided which forms a pair of air supply pathswhich lead to the conduit means. A pair of perforated plates aretransversely disposed in each air supply path and means is provided formoving one plate of one plate pair relative to the other plate in afirst sense while moving one plate of the other plate pair relative tothe other plate in a second sense to increase the proportion of airsupplied through one path while concur.- rently decreasing theproportion of air supplied through the second path.

The drawings: Other objects and intended advantages of this inventionwill be more readily appreciated as they become better understood byreference to the following detailed description in connection with theaccompanying drawings wherein:

FIG. 1 illustrates a system accordingto the present invention forindividually controlling the temperature in a plurality of adjacentrooms;

FIG. 2 illustrates a system for conditioning the temperature in aplurality of vertically disposed room zones;

FIG. 3 illustrates a system utilizing common returned air to temperaturecondition adjacently disposed room zones;

FIG. 4 is a perspective view, partially cut away, of one embodiment ofthe present invention;

FIG. 5 is a cross-sectional view of the sensing unit of the device shownin FIG. 4;

FIG. 6 is another perspective view of the device shown in FIG. 4;

FIG. 7 is a perspective sectional. view of a portion of the perforatedplates shown in FIGS. 4 and 5;

FIG. 8 is a sectioned view of another embodiment of the perforatedplates of the present invention;

FIG. 9 is a cross-sectional view of another embodiment of the perforatedplates of the present invention;

FIG. 10 is a schematic diagram of a temperature conditioning systemutilizing the present invention;

FIG. 11 is a perspective sectional view of the system embodying thedevice shown in FIG. 4;

FIG. 12 is a somewhat schematic view, partially in cross section, of thesystem shown in FIG. 11;

FIG. 13 is a cross-sectional view of another embodiment of a sensingunit of the present invention;

FIGS. 14-17 are perspective views, partially cut away, of four differenttemperature control systems utilizing perforated plate control accordingto the present invention;

FIG. 18 is a broken sectional view of adirectacting,expandible-material, temperature-sensitive device and ofpart of a remote-control system to mechanically adjust the set point ofthat temperature-sensitive device;

FIG. 19 is a broken-away sectional view of another direct-acting,expandible-material, temperaturesensitive device and of part of aremote-control system to hydraulically adjust the set point of thattemperature-sensitive device;

FIG. 20 is a broken sectional view of a furtherdirectacting,expandible-material,temperature-sensitive device and ofpart of a remote-control system to hydraulically adjust the set point ofthat temperature-sensitive device;

FIG. 21 is a broken sectional view of yet another direct-acting,expandible-fluid, temperature-sensitive device and of part of aremote-control system to mechanically adjust the set point of thattemperature-sensitive device;

FIG. 22 is a broken sectional view of a still furtherdirect-acting,expandible-material, temperature-sensitive device and ofpart of a remote-control system to electro-mechanically adjust the setpoint of that temperature-sensitive device;

FIG. 23 is a sectional view through the structure shown in FIG. 22, andit is taken along the plane indicated by the line 23-23 in FIG. 22;

FIG. 24 is a broken sectional view of still anotherdirect-acting,expandible-material, temperature-sensitive device and ofpart of a remote-control system to electrically adjust the set point ofthat temperaturesensitive device; and

FIG. 25 is a broken sectional view of an additionaldirect-acting,expandible-material, temperaturesensitive, device and ofpart of a remote-control system to electrically adjust the set point ofthat temperaturesensitive device.

The Preferred Embodiments: FIGS. 13 illustrate air temperature controlsystems wherein warm air or cool air reservoirs common to a plurality ofindividual zones to be temperature controlled may be utilized with theapplication of the present invention. FIG. 1 discloses a control systemwherein the temperature of air in several adjacently disposed rooms maybe maintained individually in accordance with their separaterequirements. A warm air reservoir or plenum 10, which may, for example,be an attic space fed by return air from rooms therebelow, is commonlydisposed to each of the rooms 12, 14, 16 and 18. Cool air is suppliedfrom a suitable source through a duct 20 which forms a cool air supplypath leading to a first control section 22 in a flow control unit 24constructed in accordance with the present invention. Warm air isreturned from the room 12 through the opening 26 to combine with thewarm air in the reservoir to form a warm air supply path leading to asecond control section 28 on the control unit 24. The control sectionseach comprise pairs of perforated plates, one slidable with respect tothe other, and so actuated as to proportion the air flowing therethroughin dependence upon temperature, as will be described in greater detail.A fan is located in the control unit 24 to pull air through the controlsections 22 and 28 in such proportions as required to control thetemperature of room 12. The air from the warm and the cool supply pathsis mixed and then supplied to room 12 through conduits 30 and 32 andthrough supply openings 34 and 36, respectively.

Also illustrated in FIG. 1 is another embodiment of a system utilizingthe present invention, wherein cool air from a duct 38 supplies aportion of air through openings 40 into'room 14, opening 42 into room16,

and opening 44 into room 18 in such proportions as determined by thecontrol units 46 and 48, constructed in accordance with the presentinvention. Warm air is returned through opening 50 from room 14 into thereservoir 10 for mixture with the cool air supplied by the duct 38 insuch proportions as is determined by the control unit 46. In a somewhatsimilar manner, warm air is supplied to an opening 52 from room 18 to bemixed with the cool air supplied by the duct 38 in such proportions asis determined by the control unit 48. The proportions of warm air andcool air are accurately controlled in response to sensing devicesexposed to air of the temperature of the air in the individual rooms,thus allowing individual temperature control of each of the adjacentlydisposed rooms.

FIG. 2 illustrates the use of the present invention in a temperaturecontrol system for a plurality of vertically disposed rooms in abuilding. A cool air reservoir or plenum 54, common to a plurality ofvertical rooms, contains cool air supplied by a blower 55 in aconventional cooling unit 56, which may utilize conventional dampers 58to control the inflow of outside air. A warm air return plenum 60contains warm exhaust air supplied by the rooms and from the cool airreservoir 54 through the grille 62. The plenum 60 is connected throughconduit 63 and suitable dampers to the cooling unit 56.

As may be seen, a system utilizing the present invention may take anyone of a variety of forms. For instance, the system for independentlycontrolling the temperature of room 64 supplies conditioned air to theinlets 66 through conduits 67, the conditioned air being mixed by thecontrol unit 68 from the warm air returned through the outlets 69 andthe cool air supplied through the path 70. A similar system is shown forconditioning the air of room 72 wherein rigid ductwork 74 is utilizedinstead of flexible conduits. If desired, a plurality of control unitsmay be utilized for conditioning a single room, as shown by the threeunits 76, 78 and 80, which selectively proportion the amount of cool airfrom the reservoir 54 and the warm air from the attic plenum 82 mixedand provided to the room.

FIG. 3 illustrates a conditioning system for a pair of rooms 84 and 86which are commonly disposed to a warm air attic reservoir 88 and a coolair reservoir 90. Warm air from rooms 84 and 86 flows to a common plenum92 and a conduit 93 and thence into a conventional cooling system 94. Ablower unit 95 supplies a continuous supply of cool air to the reservoir90. Warm air also flows from the rooms 84 and 86 into the atticreservoir 88 through openings and 87, respectively. A pair of air-mixingcontrol units 96 and 98, constructed in accordance with the presentinvention, are mounted between the warm air reservoir 88 and the coolair reservoir in order to selectively proportion the mixture of the twoair supplies which is fed into rooms 84 and 86, respectively.

While refrigeration units have been illustrated in conjunction with theembodiments described, it will be appreciated that, if desired, cold aircould be provided from an outside environment and heating means could beprovided to supply a source of warm air.

The construction of an air-mixing control unit in accordance with thepresent invention may be best understood by reference to FIGS. 4-6,wherein the unit 100 is enclosed by a main housing 102. Housing 102 isan elongated rectangular polyhedron conveniently formed of sheet metal.Housing 102 may have one or more removable panels 104 for repair ormaintenance access. A pair of conventional blower fan units 106 and 108include rotatable vaned cages 109 and 1 10 driven by an electric motor111. The operation of electric motor 111 is controlled by a suitablyplaced wall switch 112 connected through cable 113 which controls theapplication of power from a suitable source (not shown) to the motor.Rotation of the cages 109 and induces flow of supply air through a firstperforated plate unit 114 and a second perforated plate unit 116.

Perforated plate units 114 and 116, as shown in FIG. 6, are disposedrelative to one another at an angle corresponding with the junction ofwarm and cool air supply paths. Rectangular flanges 1 17 and 1 18 may beprovided about the outer openings of the plate sections in order toenable connection with air conduits. As shown in FIG. 7, plate unit 114comprises a fixed plate 122 adjacent to a slidable plate 128. Plates 122and 128 have perforations therein which may be brought into registrationor moved out of registration to open or close the air flow path and thusproportion the air passing through the housing 102. Plate unit 116includes slidable plate 139 and fixed plate 134. Air flowing through theplate units 114 and 116 is expelled by the fan units through theirrespective outlets 119 and 120.

Referring again to FIG. 7, plate unit 114 comprises a first plate 122which is fixedly connected at one edge to a bracket member 124 which isin turn connected to the main housing 102 of the unit. The other edge ofthe plate 122 is connected to housing 102 by means of a folded flange125 (FIG. 4). Plate 122 includes a plurality of elongated perforations126 defined therethrough in a predetermined alternating pattern. Asecond plate 128, comprising one-half of an integral plate having acentral right angle bend, is slidable adjacent to the plate section 122.Plate 128 is connected to the rod 130, as by welding, for slide movementrelative to plate 122.

Plate 128 includes a plurality of elongated perforations 132 disposed inthe same pattern as the perforations 126 in the plate 122, so that theperforations in the adjoining plates may be selectively brought intoregistration or moved out of registration in order to control the flowof air therethrough. In FIG. 7, the perforations 126 and 132 aredisposed in exact registration so that the passage of air therethroughis substantially unimpeded. Upon a slight vertical movement of the rod130, the perforations may be moved out of registration in order toaccurately adjust the magnitude of the air flow therethrough.

The second plate unit 116 comprises a first plate 134 rigidly secured tothe bracket member 136 and having a plurality of elongated perforations138 disposed therethrough in a predetermined pattern. The plate 134 isoffset with respect to the plate 122 so that the perforations throughthe two plates are not aligned. The second half of the bent plate, plate139, has a plurality of perforations 140 and is adjacent to the plate134. Because the perforation patterns of plates 122 and 134 are offset,when the perforations of the plate unit 114 are exactly aligned, theperforations of the second plate unit 116 are unaligned. In such case,the flow of air through the second plate unit 116 is thus totallyobstructed.

Upon movement of the rod 130, however, the plates 128 and 139 would bemoved relative to both the plates 122 and 134, thereby decreasing theproportion of air allowed to pass through the first plate unit 114,while concurrently increasing the proportion of air allowed to passthrough the second plate unit 116. It will be understood that finecontrol of the passage of air, and similar control of mixing of air fromtwo different air supply paths, may be accomplished by the presentdevice. Only a very small mechanical movement is required to change onepair of plates from open to closed. The elongated slot configurationshown in FIG. 7 has the distinct advantage of not requiring extremelyaccurate manufacturing dimensioning to provide substantial registrationof the perforations while maintaining at a minimum the travel necessaryto open and close a pair of plates.

FIG. 5 discloses means for moving rod 130 to adjust the positions of theperforated plates. A fluid filled sensor 141 is connected in fluidcommunication with a fluid chamber 142 by means of a line 144.,An insert146 within the chamber 142 limits the upward movement of the end 148 ofan elongated linkage 150. A housing 152 provides a fluid-tight sealabout the linkage 150, and a bias spring 154 is disposed between the end148 and the housing 152. A threaded portion 158 on the linkage 150provides for connection to an extension 156 on the rod 130 in order toallow initial adjustment of the position of the rod 130 for properalignment of the perforations.

A fluid conduit 160 connects the chamber 142 in fluid communication withan adjustment mechanism 162 comprising a hollow chamber 164 also filledwith the fluid. A slidable piston 166 is biased against the fluid in thechamber 164 by a spring 168. A dial 170 may be manually turned toselectively increase or decrease the tension applied by the piston 166against the fluid. The variance of pressure on the fluid acts on the end148 to move the linkage vertically. By suitable adjustment of dial 170,therefore, the static position of the, rod 130 and the outer platesections 128 and 139 may be adjusted to provide either warmer or coolerair flow.

In operation of the present unit, the dial is set to the desiredoperating temperature. The sensor 141 senses air of the temperature ofair in a room. If the temperature increases, the fluid inside the sensor141 tends to expand, overcoming the bias pressure of the spring 154 andmoving the linkage 150 downwardly. This causes the rod 130 and thus theperforated plate sections 128 and 139 to move downwardly, therebychanging the registration of the perforations. This movementconcurrently increases the amount of cool air and decreases the amountof warm air supplied to the room.

Conversely, if the temperature of the room air drops, the 'volume of thefluid inside the sensor 141 and the chamber 142 will decrease. Spring;154 moves the perforated sections 128 and 139 upward. The change causesthe temperature of the air in the room to be raised. The novelconstruction of the present invention thus allows very accurate controlof the air supply to a room in response to only a very slight mechanicalmovement. This movement is within the capabilities of theexpandible-material sensing device 141.

Other configurations of perforations may be employed in the perforatedplates. For example, FIG. 8 i1.- lustrates a plurality of substantiallycircular perforations 171 distributed in predetermined patterns throughfixed plates 172 and 173. A movable outer plate 174 is connected, as bywelding, to the rod 176 for movement relative to the fixed plates 172and 173. The plate 174 includes a plurality of circular perforationswhich may be moved into registration with the openings of only one ofthe fixed plates 172 or 173 at a time.

FIG. 8 illustrates a position of the plate 174 such that theperforations 175 are in registration with the perforations in plate 172.In this position, the perforations in plate 174 are out of registrationwith the openings of the plate 173, thereby preventing the passage ofair therethrough. It will be understood that other configurations ofperforations may also be employed for the plates, as, for example,square, rectangular, and the like.

The plates above described may advantageously be constructed of rigidmaterial, preferably of stainless steel. Plate sections of other metals,such as aluminum or the like, may also be used when corrosion will notadversely affect operation.

It may be found advantageous to construct one or more of the plates froma flexible material, in the manner illustrated in FIG. 9. In thisembodiment, the perforated plate 178 is constructed from stainlesssteel, while the perforated plate 180 is constructed from a flexiblematerial, such as neoprene-covered canvas or the like. By placing theflexible plate upstream of the rigid plate section, the pressure of theair flow against the flexible plate will press it against the rigidplate, thereby minimizing the loss of air through the space be tween theplates. Alternatively, a felt-like material may be bonded to one side oftwo stainless steel plates of a pair, and between them, in order to cutdown air loss and to resist corrosion.

FIG. 10 illustrates another embodiment of a sensing apparatus for usewith the present control unit 181 above described for control of thetemperature in room 184. A bimetallic circuit controller 185 is mountedon the wall 187 or in some other suitable place in order to sense thetemperature of air in room 184. Such a bimetallic controllerconventionally changes from one position to another in order to open orclose an electrical contact (not shown). The controller 185 serves toenergize and de-energize a servo motor 186 which is connected through amechanical linkage 188 to the movable perforated plate sections 182 and183. Energization of the servo motor 186, also of a conventionalconstruction, selectively varies the alignment of the perforations inthe plate sections in order to control the content of the air beingsupplied to room 184.

FIGS. 11 and 12 illustrate a system utilizing the sensing device shownin FIG. 5. In this application, the control unit 190 has perforatedplate sections 191 and 192 operated in dependence upon anexpandible-material sensor 193. Sensor 193 is disposed in an air conduit194 which could be a short length of thin-wall electrical conduit. Theconduit 194 is connected at one end to a wall panel box 196 having aperforated front panel 198 to allow the passage of air from a roomtherethrough. The wall panel box 196 can be an electrical outlet box ofstandard design. The other end of the air conduit 194 is connected to ajunction box 200 mounted on the unit 190. Electric power from a suitablesource may be provided to energize the blower fans in the unit 190through cables 204 and 206.

An electrical switch 208 is remotely disposed from the unit 190 and ismounted on the perforated panel 198 in order to allow remoted adjustmentof the speed of the blower in unit 190. Similarly, a temperatureselector mechanism 210, similar to that shown in FIG. 5, in fluidcommunication with the expandible liquid sensor 193, is mounted on theperforated panel 198 in order to allow remote adjustment of thetemperature of the air of the room.

The wall panel box 196 ordinarily will be mounted in the space betweenroom wall panels 212 and 214. The end of the air conduit 194 connectedto the junction box 200 is disposed upstream of the blower of the unit190 so that room air passes through the conduit 194 and flows over thesensor 193. If desired, the remote end of the conduit 194 may bedisposed between the wall panels 212 and 214 in order to sample warm airfrom the room being returned to a warm air reservoir. Alternatively, thesensor 193 may be disposed in a region downstream from the blower fansof the unit 190 in order to sample the air flow to a given room.

FIG. 13 illustrates another embodiment of a suitable temperature sensorfor mechanically moving perforated plates relative to one another. Ahousing 216 includes an inlet port 218 for entry of air whosetemperature is to be sampled and further includes an annular ring 221having outlet ports 220 for exhausting air.

A temperature-sensitive device 222 contains an expandible material andmay be of the type presently or formerly manufactured byAmerican-Standard Control Division, Detroit, Mich., and sold under thename Vernatherm. Alternatively, the temperature-sensitiveexpandible-material device manufactured by The Dole Valve Company,Morton Grove, 111. or the temperature-sensitive expandible-materialdevice manufactured by Fulton Sylphon Division of Robertshaw,

Knoxville, Tenn. could be used as the temperaturesensitive unit 222.Unit 222 is mounted on a bracket 224. A piston 226 is movable into andout of unit 222 in response to expansion of the material therein inresponse to temperature changes. A pin 228 is connected to the piston226 and includes a threaded portion 230 adapted to connect to a rod 232.Rod 232 is to be connected to the movable perforated plates abovedescribed. A sleeve 234 abuts a cup 236 which is biased by a spring 238.A base cup 240 abuts the lower end of spring 238 and has a centralopening through which pin 228 passes.

The base cup 240 includes a threaded section 242 which threadedly mateswith threads in the annular ring 221. Ring 221 also includes a threadedportion 244 which mates with threads in the housing 216. The threadedportions 242 and 244 may be provided with threads of different pitch toallow for initial adjustment of the static position of the sensingdevice. A coarse adjustment may be made by rotation of the annular ring221. A fine adjustment may be made by rotation of the base member 240relative to the ring 221.

The sensor illustrated in FIG. 13 preferably is mounted on or near acontrol unit and is mechanically linked to movable perforated platesthrough the rod 232. The unit of FIG. 13 may be mounted in the conduitopening into a room in order to sense the temperature of the air beingsupplied to the room. Alternatively, it may be mounted in or near thereturn paths from a room. In each of these embodiments, a mechanicallinkage may connect the cup 240 to a readilyaccessible manually operablewall-mounted actuator or control knob to allow adjustment of the setpoint.

Other applications of the present invention will be apparent uponconsideration of FIGS. 14-17, wherein perforated plate control accordingto the present invention is utilized in four different types oftemperature control systems. FIG. 14 illustrates a supply grille orconduit 246 which has a rectangular frame 248 adapted to be releasablymounted in a supply opening leading to a room. A warm air supply path250 is partially defined by a duct collar 252 having insulation 254installed therein. A cool air supply path 256 is located beneath thewarm air supply path 250 and is defined by the collar 252 and aninsulated divider partition 258.

The two air supply paths 250 and 256 are fed into the room from suitablesources through pairs of perforate plates constructed in accordance withthe present invention. More particularly, an integral perforated plate260 is rigidly mounted between the frame 248 and a bracket 262 connectedto the duct collar 252. A pair of movable perforated plates 264 and 266are slidably disposed in a groove in the bracket 262 and are connectedto the horizontally movable bar 268. Thus, a first pair of perforatedplates comprising the upper portion of plate 260 and the movable plate264 is transversely disposed in the warm air path 250. Similarly, asecond pair of perforated plates comprising the lower portion of thefixed perforated plate 260 and the movable plate 266 is transverselydisposed in the cool air supply path. The plate section pairs may thusbe relatively moved, in the manner previously described, to selectivelyadjust the registration of the perforations in adjacent plates tocontrol the mixture of warm and cool air which is supplied to the room.

The force for moving bar 268 is provided by the power unit 270, whichmay, for instance, be of the expandible fluid or material typepreviously described. Pressure resulting from fluid expansion in thepower unit 270 acts upon the head 272 of a rod 274. A spring 276 biasesthe head 272 against the bottom of the lower housing 278 of the powerunit. The lower end of rod 274 is connected to a threaded member 280 byadjusting nut 282 in order to allow initial adjustment of the positionof the perforated plates. The threaded member 280 is connected to aprojection 284 from bar 268 by a plurality of screws 286. The frame 248and the fixed perforated plate 260 are thus made to be easily removedfor maintenance purposes. More particularly, screws 286 are disposed tobe easily accessible upon the removal of frame 248 and plate 260 toallow the movable plates 264 and 266 to be removed for servicmg.

FIG. illustrates the use of perforated plates in a temperature controlsystem wherein cool air is forced into a room through a nozzle 288 and aduct 290. Return air from a warm air plenum may be selectively mixedwith the cool air by means of a venturi type action created by the flowof air through the nozzle 288. This venturi action induces flow of warmair into the duct 290 through the perforated plate pairs 292 and 294.

The perforated plate pairs include a horizontally slidable plate 296which is transversely disposed across both of the warm return air pathsand also across the cool air supply path. Plate 296 is connected to aguide bar 298 which is horizontally slidably mounted upon a frame member300 which rigidly connects nozzle 288 to the front duct frame 301. Apower unit 302 is connected to move the rod 304, which in turn moves aprojecting member 306 and bar 298.

A perforated plate 308 is mounted in the duct 290 adjacent to themovable perforated plate 296. The

fixed perforated plate 308 may comprise a unitary plate having apredetermined pattern of aligned perforations at the top and the bottomportions of the plate which are disposed adjacent the movable plates 292and 294, and a pattern of horizontally offset perforations in the middleportion of the plate which is disposed transversely across the openingof the nozzle 288.

Alternatively, the movable plate 296 may comprise three sheets mountedadjacent to each other, with the perforations of the top and bottomplate sections being aligned and the perforations of the middle platebeing horizontally offset. In either embodiment, it will now be apparentthat when the movable perforated plate 296 is horizontally translated inresponse to changes of air temperature in the room to be conditioned,the proportion of cool air supplied through the duct 290 may beselectively modulated in one sense while the porportion of warm returnair is concurrently modulated in the op- I posite sense.

FIG. 16 illustrates another type of temperature control system 310,generally known as a double duct constant volume system. Warm air undera high pressure is fed through the supply inlet 312 into the housing314, while cool air under high pressure is supplied through the inlet316. A partition 318 divides the air supply paths inside the frontportion of the housing 314. The warm and the cool air are then mixed inthe back portions of the housing 314 in proportions determined bytransversely disposed perforated plates 320 and 322. The plate 322 isrigidly connected to the housing 314. Plate 320 is movable in responseto movements of the temperature sensitive power unit 324. The power unit324 moves the movable plate 320 by means of a projection 326 mounted ona transversely disposed bar 328 rigidly connectedto plate 320. The bar328 is slidable through a slot 330in the partition 318.

The perforated plates are supported by a spacer member 332 which hasprovisions to allow a sliding movement of the plate 320. Theperforations in the movable plate disposed in the warm air supply pathare horizontally offset with respect to the perforations in the movableplate disposed inthe cool air supply path. This allows the proportion ofair supplied to the room by the warm air supply path to be selectivelyincreased while concurrently the proportion of air supplied to the roomby the cool air supply path is decreased, or vice versa.

FIG. 17 illustrates the use of the present invention in a temperaturecontrol system commonly termed a high velocity induction unit. In thissystem, a bypass control simultaneously modulates the amount of returnroom air which passes over heating or cooling coils and the amount ofreturn room air bypassed around the coils. For example, in theillustrated system of FIG. 17, return room air is induced to flowthrough a grille 333 and then through perforated plate units 334 and336. Air flow through plates 334 bypasses the heating or cooling coilsin zone 337.

A baffle 338 separates the two flows of air. Air passing through plates336 contacts the heat exchange elements in zone 337. The perforatedplate pairs are constructed in a manner similar to the units previouslydescribed, with a slidable plate 340 being connected to a bracket 342which is horizontally moved by a power unit 343. The bracket 342 slidesalong an edge portion of the baffle338. A fixed plate 344 is connectedto the frame 346.

It will be understood from the embodiments previously described that theperforations of one perforated plate section in each of the perforatedplate pairs 334 and 336 are horizontally offset with respect to oneanother so that the proportion of room air return supplied through onepath may be concurrently increased while the proportion of room airreturn supplied through the second path is concurrently decreased.

Referring particularly to FIG. 18, the numeral 400 denotes one wall ofan air-mixing control unit such as the air-mixing control unit of FIGS.11 and 12. A generally-cylindrical housing 402 is suitably secured tothe wall 400, adjacent an opening in that wall, by selftapping metalscrews; and an air conduit 404 such as the air conduit 194 in FIGS. 11and 12 is secured to the end wall of the housing 402. A strut 406extends transversely of the housing 402; but that strut does not preventthe flow of air through that housing, because the width of that strut isonly about one-third the inner diameter of that housing.

The numeral 408 denotes an externally-threaded sleeve which is mountedwithin an opening in the strut 406; and a cup-like bracket 410 has aninternal thread at the right-hand end thereof which mates with theexternal thread on the sleeve 408. That cup-like bracket has a thread412 at the left-hand end thereof which mates with an external thread 416of a directacting,expandible-material, temperature-sensitive device 414which can be a Vernatherm unit. The numeral 417 denotes the actuator ofthat temperature-sensitive device; and the numeral 418 denotes aflexible cable which is secured to the housing of that temperaturesensitive device. That cable can be of the type used in the speedometersof automotive vehicles; and it will have its left-hand end connected toa knob or dial, not shown, located in or close to the space or roomwhich is supplied with air by the air-mixing control unit.

The numeral 420 denotes a nut which has an internal thread that mateswith the external thread on the sleeve 408. A threaded bushing 422 isheld by an internal thread of the nut 420; and that bushing accommodatesa reciprocable rod 424. A washer 428 is mounted on the left-hand end ofthe rod 424; and a helical compression spring 426 has one end thereofbearing against that washer and has the other and thereof bearingagainst the bushing 422. The spring 426 biases the spherical surface ofthe head of the rod 424 into engagement with the right-hand end of theactuator 417 of the temperature-sensitive device 414. However, thatspring can yield to permit movement of the rod 424 to the right inresponse to right-hand movement of the actuator 417.

The air conduit 404 will have the left-hand end thereof in communicationwith the space or room which is supplied with air by the air-mixingcontrol unit 400, in the same manner in which the air conduit member 194of FIGS. 11 and 12 is in communication with the room which is suppliedwith air by the air-mixing control unit 190. As a result, return airwill be drawn through the air conduit 404 past the temperaturesensitivedevice 414, through the housing 402, and then through the opening in thewall 400. That air will cause the actuator 417 of that temperaturesensitive device to assume a position corresponding to the temperatureof that air; and the rod 424 will respond to that position toappropriately set the perforated plates or movable dampers within theair-mixing control unit. The temperature-sensitive device 414 will beessentially inaccessible from the space or room served by the airmixingcontrol unit; but the flexible cable 418 will enable a maintenance manwithin that space or room to adjust the set point of thetemperature-sensitive device 414. To adjust that set point, themaintenance men will actuate the knob or dial in the room to cause thecable 418 to rotate the housing of the temperature-sensitive device 414.As that housing rotates, the thread 416 thereon will coact with thethread 412 of the cup-like bracket 410 to axially displace the actuator417, with a consequent displacement of the rod 414. The resultingadjustment of the position of the perforated plates or movable damperswill shift the proportion of warm air introduced into the space or roomto the desired value. a To lower the set point of thetemperature-sensitive device 414, the housing of thattemperature-sensitive device will be rotated to cause that housing toshift a short distance to the right in FIG. 18. The resulting axialdisplacement of the actuator 417 will force the spring 426 to yield andpermit a corresponding axial displacement of the rod 224. The perforatedplates or movable dampers will respond to that displacement of that rodto decrease the proportion of warm air in the air which the air-mixingcontrol unit supplies to the space or room. As a result, the temperatureof the air within the space or room will decrease to a lower averagevalue.

As the temperature of the air within that space or room decreases, thetemperature of the air flowing through the air conduit 404 will decreasecorrespondingly. The expandible fluid within the temperaturesensitivedevice 414 will respond to that decrease in temperature to experience adecrease in the volume thereof; and hence the actuator 417 will shift tothe left in FIG. 18. However, the shifting of that actuator to the rightin response to the rotation of the housing of the temperature-sensitivedevice will be greater than the shifting of that actuator to the left,in response to the reduction in the temperature of the air in the airconduit 404. As a result, the set point of the temperaturesensitivedevice 414 will have been lowered; and hence the average value of thetemperature of the air within the space or room will have been reduced.

If the average temperature within the space or room is to be increased,the maintenance man will use the knob or dial within that space or roomto cause the cable 418 to rotate the housing of the temperaturesensitivedevice 414 in the opposite direction. The resulting shift of thathousing to the left will enable the spring 426 to shift the rod 424 tothe left. Thereupon the perforated plates or movable dampers within thehousing of the air-mixing control unit will supply a higher percentageof warm air and hence the average temperature within the space or roomwill be increased.

As the temperature of the air within that space or room increases, thetemperature of the air flowing through the air conduit 404 will increasecorrespondingly. The expandible-material within the temperaturesensitivedevice 414 will respond to that increase in temperature to experience anincrease in the volume thereof; and hence the actuator 417 will shift tothe right in FIG. 18. However, the shifting of that actuator to theleft, in response to the rotation of the housing of thetemperature-sensitive device 414, will be greater than the shifting ofthat actuator to the right, in response to the increase in thetemperature of the air in the air conduit 414. As a result, the setpoint of the temperature-sensitive device 414 will have been increased;and hence the average value of the temperature of the air within thespace or room will have been increased.

()nce the set point of the temperature-sensitive device 414 has beenset, that temperature-sensitive device will automatically operate tomaintain a corresponding average temperature within the space or room.If the temperature of the air within the space or room tends to fallbelow that average temperature, the temperature of the air flowingthrough the air conduit 404 will decrease; and the resulting reductionin volume of the expandible material within the temperaturesensitivedevice 414 will permit the actuator 417 to move to the left. The spring426 will provide a corresponding movement of the rod 424 to the leftwith a consequent increase in the proportion of warm air introduced intothe space or room by the air-mixing control unit. The overall result isthat the temperature of the air within the space or room will move backup to the desired level, and the actuator 417 and rod 424 will return totheir'set positions. Conversely, if the temperature of the air withinthe space or room tends to rise above the average temperature, thetemperature of the air flowing through the air conduit 404 willincrease; and the resulting increase in volume of the expandiblematerial within the temperature-sensitive device 414 will cause theactuator 417 to shift to the right. The

spring 426 will yield to permit a corresponding shift of the rod 424 tothe right with a consequent decrease in the proportion of warm airsupplied to the space or room by the air-mixing control unit. Theoverall result is that the temperature of the air within the space orroom will move back down to the desired level, and the actuator 417 androd 424 will return to their set positions.

It thus should be apparent that by using the structure in FIG. 18, it iseasy to adjust the set point of the temperature sensitive device 414from a point within the space or room. This is important because thattemperature-sensitive device is essentially inaccessible from that spaceor room being located immediately adjacent the wall 400 of theair-mixing control unit.

The left-hand end of the air conduit 404 will preferably be in directcommunication with the space or room, as indicated by FIGS. 11 and 12;so air from that space or room can pass directly into that air conduitand thence directly to the temperature-sensitive device 414. To minimizecosts of installation, the cable 418 will usually be located within thatair conduit; and the knob or dial on that cable will usually be mountedon a perforated plate at the outer face of a wall panel box to whichthat air conduit is connected. However, if desired, the cable 418 couldhave a substantial portion of the length thereof disposed outwardly ofthe air conduit 418; and it could have the knob or dial therefor locatedin a box or panel which was located in a corridor or hall exteriorly ofthe space or room.

FIG. 19 shows a remote-control arrangement which is specificallydifferent from the remote-control arrangement of FIG. 18, although someof the components thereof are identically numbered and can be identical.The numeral 432 denotes L-shaped brackets which are secured to the innersurface of the cylindrical housing 402; and those brackets fixedlysupport an annular plate 434 which has a concave annular recess 436 inthe right-hand face thereof. A liquid-tight annulus 438 of expandiblematerial is cemented or otherwise secured in position within the concaveannular recess 436; and a concave annular recess 442 in the left-handface of a circular plate 440 also is cemented or otherwise secured tothat expandible annulus. The circular plate 440 is supported by theexpandible annulus 438, but it is biased toward the annular plate 434 byspring clips 443 which are suitably secured to the inner surface of thehousing 402.

The circular plate 440 has air passages 444 therethrough, and also has acentral passage which accommodates an externally-threaded sleeve 446.Nuts 448 are threaded onto that sleeve in abutting engagement with theopposite faces of that circular plate to fixedly secure that sleeve tothat plate. A nut 450 is threaded onto the left-hand end of the sleeve446, and the external thread 454 of a temperature-sensitive device 452,which can be a Vernatherm unit. is held by an internal thread of thatnut. The spring 426 holds the head of the rod 424 in engagement with theactuator 456 of that temperature-sensitive device. The numeral 458denotes a hollow tube which has the right-hand end thereof connected tothe expandible annulus 438, and which has the lefthand end thereofconnected to a transducer 468 that responds to the rotation of a knob470 to change the pressure on the liquid therein and thus on the liquidwithin the tube 458 and within the expandible annulus 438. Thetransducer 468 is located within a wall box 460 that is disposed betweentwo walls 464 and 466; and the front of that wall box is covered by aperforated plate 462 which can be identical to the plate 198 in FIGS. 11and 12.

The perforated plate 462 will preferably be located in the space or roomwhich is supplied with air by the air-mixing control unit of which thewall 400 is a part. That air-mixing control unit will draw some of thereturn air from that space or room through the perforations of thatplate, through the air conduit 404, past the temperature-sensitivedevice 452, through the center of the annular plate 434, through theopenings 444 of the circular plate 440, and then through the opening inthe wall 400. That air will cause the expandible material within thattemperature-sensitive device to assume a volume comparable to thattemperature.

To adjust the set point of the temperature-sensitive device 452, themaintenance man will rotate the knob 470, and will thereby change thepressure on the liquid within the transducer 468, within the tube 458,and within the expandible annulus 438. If that maintenance man rotatesthe knob 470 in a direction which reduces the pressure within theexpandible annulus 438, the spring clips 443 will reduce the thicknessof that expandible annulus by shifting the circular plate 440 to theleft; and thus will shift the sleeve 446, the nut 450, thetemperature-sensitive device 452, the spring 426 and the rod 424 to theleft. That shift will cause the perforated plates or movable damperswithin the airmixing control unit to increase the proportion of warm airwhich that air-mixing control unit will supply to the space or room.Consequently, the average temperature of the air within that space orroom will increase.

As the temperature of the air within that space or room increases, thetemperature: of the air flowing through the air conduit 404 willincrease correspondingly. The expandible fluid within thetemperaturesensitive device 452 will respond to that increase intemperature to experience an increase in the volume thereof; and hencethe actuator 456 will shift to the right in FIG. 19. However, theshifting of that actuator to the left, in response to the reduction inthickness of the expandible annulus 438, will be greater than theshifting of that actuator to the right, in response to the increase inthe temperature of the air in the air conduit 404. As a result, the setpoint of the temperaturesensitive device 452 will have been raised; andhence the average value of the temperature of the air within the spaceor room will have been increased.

If the maintenance man rotates the knob 470 in a direction whichincreases the pressure within the expandible annulus 438, the thicknessof that expandible annulus will increase with a consequent shift ofcircu lar plate 440, sleeve 446, nut 45 0, the temperaturesensitivedevice 452, spring 426 and rod 424 to the right. That shift will causethe perforated plates or movable dampers within the air-mixing controlunit to decrease the proportion of warm air which that air-mixingcontrol unit will supply to the space or room. Consequently, the averagetemperature of the air within that space or room will decrease.

As the temperature of the air within that space or room decreases, thetemperature of the air flowing through the air conduit 404 will decreasecorrespondingly. The expandible material within the temperaturesensitivedevice 452 will respond to that decrease in temperature to experience adecrease in the volume thereof; and hence the actuator 456 will shift tothe left in FIG. 19. However, the shifting of that actuator to theright, in response to the increase in thickness of the expandibleannulus 438, will be greater than the shifting of that actuator to theleft, in response to the decrease in the temperature of the air in theair conduit 404. As a result, the set point of the temperature-sensitivedevice 452 will have been lowered; and hence the average value of thetemperature of the air within the space or room will have beendecreased.

Once the set point of the temperature-sensitive device 452 has been set,that temperature-sensitive device will automatically operate to maintaina corresponding average temperature within the space or room in themanner described hereinbefore in connection with FIG. 18. It thus shouldbe apparent that by using the structure in FIG. 19, it is easy to adjustthe set point of the temperature-sensitive device 452 from a pointwithin the space or room. This is important because thattemperature-sensitive device is essentially inaccessible from that spaceor room.

FIG. shows a remote control arrangement which is specifically differentfrom the remote-control arrangement of either of FIGS. 18 and 19,although some of the components thereof are identically numbered and canbe identical. The external thread 454 of a temperature-sensitive device452 is mounted within the internal thread 412 of a cup-like bracket 410,and that cup-shaped bracket has a slot 459 therein which accommodatesthe inlet fitting ofa hydraulic cylinder 472 that has a piston 474. Thathydraulic cylinder is dimensioned so it can slide freely within thecup-like bracket 410; and the actuator 456 of the temperature-sensitivedevice 452 bears against the closed end of that hydraulic cylinder,while the piston 474 bears against the head of the rod 424. Theair-mixing control unit, of which the wall 400 is a part, will draw airthrough the air conduit 404, past the temperature-sensitive device 452,and past the strut 406 through the opening in the wall 400. Thetemperature of that air will cause the expandible-material within thattemperature-sensitive device to assume a volume which is comparable tothat temperature.

The spring 426 urges the head of the rod 424 against the piston 474 ofthe hydraulic cylinder 472, and thereby urges the left-hand end of thathydraulic cylinder against the actuator 456 of the temperaturesensitivedevice 452. To adjust the set point of that temperature-sensitivedevice, the maintenance men will rotate the knob of a pressuretransducer, such as the pressure transducer 468 in FIG. 19, to changethe pressure on the hydraulic liquid within the hydraulic cylinder 472.If that knob is rotated to reduce the pressure on that hydraulic liquid,the spring 426 will be able to force the piston 474 further into thehydraulic cylinder 472 and will thereby be able to shift the rod 424further to the left with a consequent increase in the set point of thetemperature-sensitive device 452. On the other hand, if the knob of thepressure transducer is rotated to increase the pressure on the hydraulicfluid within the hydraulic cylinder 472, the piston 474 will force thespring 426 to yield and permit the rod 424 to shift to the right with aconsequent decrease in the set point of the temperature-sensitive device452. In this way, the set point of that temperature-sensitive device canbe set at any desired level by merely rotating the knob of thetransducer.

When the set point of the temperature-sensitive device 452 is beingincreased, the temperature of the air flowing through the air conduit404 will increase; and that temperature-sensitive device will tend toshift the rod 424 to a position wherein the proportion of warm air willbe reduced. Conversely, as that set point is being decreased, thetemperature of the air flowing through the air conduit 404 willdecrease; and that temperature-sensitive device will tend to permit thespring 426 to shift the rod 424 to a position wherein the proportion ofwarm air will be increased. However, because the movement of the piston474 can be much greater than temperature-induced movement of theactuator 456, the change in the set point of the temperature-sensitivedevice 452 will be essentially controlled by the movement of that pistonrather than by the temperature-induced movement of the actuator 456.

Once the set point of the temperature-sensitive device 452 in FIG. 20has been set, that temperaturesensitive device will automaticallyoperate to maintain a corresponding average temperature within the spaceor room in the manner described hereinbefore in connection with FIG. 18.It thus should be apparent that by using the structure in FIG. 20 it iseasy to adjust the set point of the temperature-sensitive device 452from a point within the space or room. This is important because thattemperature-sensitive device is essentially inaccessible from that spaceor room.

FIG. 21 shows a remote control arrangement which is specificallydifferent from the remote-control arrangements of FIGS. 1820, althoughsome of the components thereof are identically numbered and can beidentical. The external thread 454 of a temperaturesensitive device 452is mounted within the internal thread 412 of a cup-like bracket 410, andthat cupshaped bracket has a long slot 477 in the bottom thereof whichaccommodates the crank arm 482 of generally-elliptical cam 480. Abearing element 476, which is generally cylindrical in form but whichhas a frusto-conical right-hand end, is slidably interposed between theactuator 456 of the temperature-sensitive device 452 and the cam 480. A'bearing element 478, which is generally cylindrical in form but whichhas a frusto-conical left-hand end and a reduced diameter cylindricalright-hand end, is slidably interposed between the cam 480 and the headof the rod 424. A flexible cable 484 has the right-hand end of thereciprocable center element thereof connected to the crank arm 482; andit will have the left-hand end of that center element suitably connectedto a lever, knob or dial, not shown. A bracket 486 holds the sheath ofthat flexible cable against shifting relative to the crank arm 482.

The spring 426 will urge the head of the rod 424 against the right-handface of the bearing element 478, will urge the left-hand face of thatbearing element into engagement with the cam 480, will urge that caminto engagement with the right-hand face of the bearing element 476, andwill urge the left-hand face of that bearing element into engagementwith the actuator 456. Whenever the crank arm 482 is in the solid-lineposition of FIG. 21, the rod 424 will be in a position where only alimited proportion of warm air will be supplied to the space or room bythe air-mixing control unit of which the wall 400 is a part. However,whenever that crank arm is in the dotted-line position in FIG. 21, therod 424 will be spaced to the left of the position shown in that FIGURE,and it will permit a large proportion of warm air to be introduced intothat space or room. As a result, by appropriate manipulation of thelever, knob or dial which is connected to the left-hand end of thereciprocable inner element of the cable 484, a maintenance man can setany desired set point for the temperature-sensitive device 452.

When the set point of the temperature-sensitive device 452 is beingincreased, the temperature of the air flowing through the air conduit404 will increase; and that temperature sensitive device will tend toshift the rod 424 to a position wherein the proportion of warm air willbe reduced. Conversely, as that set point is being decreased, thetemperature of the air flowing through the air conduit 404 willdecrease; and that temperature-sensitive device will tend to permit thespring 426 to shift the rod 424 to a position wherein the proportion ofwarm air will be increased. However, because the movement of the cam 480can be much greater than temperature-induced movement of the actuator456, the change in set point of the temperaturesensitive device 452 willbe essentially controlled by the movement of that cam rather than by thetemperature-induced movement of the actuator 456.

Once that set point has been set, that temperaturesensitive device willautomatically operate to maintain.

a corresponding average temperature within the space or room. If thetemperature of the air within the space or room tends to fall below thataverage temperature, the temperature of the air flowing through the airconduit 404 will decrease; and the resulting reduction in volume of theexpandible material within the temperature-sensitive device 452 willpermit the actuator 456 to move to the left. The spring 426 will thenshift rod 424, bearing element 478, cam 480 and bearing element 476 tothe left with a consequent increase in the proportion of warm airintroduced into the space or room by the air-mixing control unit. Theoverall result is that the temperature of the air within the space orroom will move back up to the desired level, and the actuator 456 androd 424 will return to their set positions. Conversely, if thetemperature of the air within the space or room tends to rise above theaverage temperature, the temperature of the air flowing through the airconduit 404 will increase; and the resulting increase in volume of theexpandible material within the temperature-sensitive device 452 willcause the actuator 456 to shift to the right. The spring 426 will yieldto permit a corresponding shift of bearing element 476, cam 480, bearingelement 478 and rod 424 to the right with a consequent decrease in theproportion of warm air supplied to the space or room by the airmixingcontrol unit. The overall result is that the temperature of the airwithin the space or room will move back down to the desired level, andthe actuator 456 and rod 424 will return to their set positions.

It thus should be apparent that by using the structure in FIG. 21, it iseasy to adjust the set point of the temperature-sensitive device 452from a point within the space or room. This is important, because thattemperature-sensitive device is essentially inaccessible from that spaceor room.

FIGS. 22 and 23 show a remote control arrangement which is specificallydifferent from the remote-control arrangement of each of FIGS. 18-21,although some of the components thereof are identicallynumbered and canbe identical. The circular plate 440 differs from the similarly-numberedplate in FIG. 19 in having inclined planes 490, rather than anexpandible annulus, secured to the left-hand face thereof. Thoseinclined planes engage inclined planes 492 which are part of a framethat includes vertically-directed spacers 493. That frame is confinedand guided on the left by the fixed annular plate 434, and it isconfined and guided on the right by the inclined planes 490. Helicalextension springs 496 bias that frame upwardly toward the top of thehousing 402.

The numeral 498 denotes a nut which is fixedly secured to the uppersurface of the housing 402; and that nut surrounds an opening in thatupper surface. That nut receives the external thread on atemperaturesensitive device 500 such as a Vernatherm unit. A heatingcoil 502 is mounted in heat-exchanging relation with thetemperature-sensitive device 500; and conductors 508 extend between thatheating coil and an adjustable power source, not shown, which is mountedbehind a control panel 504 and which is controlled by a knob 506. Whilevarious forms of adjustable power sources could be used to control theamount of current flowing through the heating coil 502, one of thestandard light dimmers, which are mounted in electrical outlet boxes tocontrol the lights within rooms in residences, could be used. Also, ifdesired, a silicon controlled rectifier and a firing circuit thereforcould be used to vary the amount of power supplied to the heating coil502.

The spring clips 443 will urge the circular plate 440 to the left inFIG. 22, and thus will cause the inclined planes-490 to applyupwardly-directed forces to the inclined planes 492. In addition, thesprings 496 will apply upwardly'directed forces to the inclined planes492. However, the actuator of the temperature sensitive device 500overlies and bears against the up permost inclined plane 492, andthereby limits the extent to which those inclined planes can moveupwardly. As the inclined planes 490 respond to the forces from thespring clips 443 to apply upwardly-directed forces to the inclinedplanes 492, the latter inclined planes will apply downwardly-directedforces to the inclined planes 490, and thus to the circular plate 440.The rod 424 will resist those downwardly-directed forces; but, ifdesired, anti-friction skids or rollers could be provided at the loweredge of the lower inclined plane 490 to keep'those inclined planes fromshifting downwardly from the position shown in FIGS. 22 and 23.

To adjust the set point of the temperature-sensitive device 452 in FIGS.22 and 23, the maintenance man will shift the knob 506 to a desiredposition. Specifically, to raise the set point of thattemperature-sensitive device, the maintenance man will shift the knob506 to a position wherein less current will flow through the heatingcoil 402. Thereupon, the volume of the expandible material within thetemperature-sensitive device 500 will decrease; and the springs 496 willmove the inclined planes 492 and the actuator of the lattertemperature-sensitive device upwardly. The spring clips 443 then willshift the inclined planes 490 and the circular plate 440 to the left;and the resulting shift of the rod 424 to the left will increase theproportion of warm air which the air-mixing control unit, of which thewall 400 is a part, will introduce into the space or room. Theconsequent increase in the temperature of the air flowing into thehousing 402 from the air con duit 404 will cause the expandible materialwithin the temperature-sensitive device 452 to expand, and to actthrough the actuator of that temperature-sensitive device to shift therod 424 to the right. However, the change in the temperature of theexpandible material within the temperature-sensitive device 500 will beso much greater than the change in the temperature of the materialwithin the temperature-sensitive device 452 that the new set point ofthe latter temperaturesensitive device will provide an increase in theproportion of warm air introduced into the space or room.

Conversely, to lower the set point of the temperature-sensitive device452 in FIG. 22 and 23, the maintenance man will shift the knob 506 to aposition wherein more current will flow through the heating coil 502.The resulting increase in volume of the expandible material within thetemperature-sensitive device 500 will force the actuator of thattemperature-sensitive device and the inclined planes 492 to movedownwardly. The consequent shift of the inclined planes 490 to the rightwill cause the sleeve 446 to shift the rod 424 to the right, and therebymove the perforated plates or movable dampers of the air-mixing controlunit to reduce the proportion of warm air introduced into the space orroom. The resulting reduction in the temperature of the air flowingthrough the air conduit 404 will permit the expandible material withinthe temperature-sensitive device 452 to contract; and the helicalcompression spring 426 within the sleeve 446 will shift the rod 424 tothe left. However, the change in the temperature of theexpandible-material within the temperaturesensitive device 500 will beso much greater than the change in the temperature of the expandiblematerial within the temperature-sensitive device 452 that the new setpoint of the temperature-sensitive device 452 will provide a decrease inthe proportion of warm air introduced into the space or room.

FIG. 24 shows the temperature-sensitive device 414 of FIG. 18 equippedwith a heating coil 502 rather than with the flexible cable 418.Conductors 508 extend from that heating coil to a variable-power source,not shown, such as that which is controlled by the knob 506 in FIG. 22.To adjust the set point of the temperaturesensitive device 414 in FIG.24, the maintenance man will actuate that variable-power source tochange the amount of current flowing through the heating coil 502.

If the maintenance man actuates the variable-power source to decreasethe current flowing through the heating coil 502 in FIG. 24, the volumeof the expandible material within the temperature-sensitive device 414will decrease; and the spring 426 will shift the rod 424 and theactuator 417 to the left with a consequent increase in the proportion ofwarm air introduced into the space or room by the air-mixing controlunit of which the wall 400 is a part. As a result, the set point of thattemperature-sensitive device will have been raised. However, if themaintenance man actuates the variable-power source to increase thecurrent flowing through the heating coil 502 in FIG. 24, the resultingincrease in the volume of the expandible material within thattemperature-sensitive device will shift the actuator 417 and the rod 424to the right with a consequent decrease in the proportion of warm airintroduced into the space or room. As a result, the set point of thattemperature-sensitive device will have been lowered.

When the set point of the temperature-sensitive device 414 is beingincreased, the temperature of the air flowing through the air conduit404 will increase; and that temperature-sensitive device will tend toshift the rod 424 to a position wherein the proportion of warm air willbe reduced. Conversely, as that set point is being decreased, thetemperature of the air flowing through the air conduit 404 willdecrease, and that temperature-sensitive device will tend to permit thespring 426 to permit the spring 426 to shift the rod 424 to a positionwherein the proportion increased, in the temperature of the expandiblematerial within the temperature-sensitive device 414, due to the changein current flow through the heating coil 502, will be so much greaterthan the change in that expandible material due to changes intemperature of the air flowing through air conduit 404, the set point ofthe temperature sensitive device 414 will be essentially controlled bythe heat from the heating coil 502.

Once the desired set point has been established for thetemperature-sensitive device 414 in FIG. 24, that temperature sensitivedevice will respond to the temperature of the air flowing through theair conduit 404 to appropriately adjust the position of the rod 424. Asa result, that temperature-sensitive device will be able to maintain thedesired temperature level within the space or room.

FIG. 25 shows a temperature-sensitive device 510 disposed within acup-like bracket 410 in lieu of the hydraulic cylinder 472 of FIG. 20 orof the rotatable cam 480 and the bearing elements 476 and 478 of FIG.21. The actuator 512 of the temperature-sensitive device 510 is alignedwith, and abuts, the actuator 456 of a temperature-sensitive device 452which has the external thread 454 thereof mounted within an internalthread at the left-hand end of that cup-shaped bracket. The helicalcompression spring 426 within the cupshaped bracket 410 urges the headof the rod 424 against the housing of the temperature-sensitive device510 and thereby urges the actuator 512 of that temperature-sensitivedevice into abutting engagement with the actuator 456 of thetemperature-sensitive device 454. A heating coil 502 is wound around thehousing of the temperature sensitive device 510; and conductors 508extend to a variable power source such as the variable-power sourcecontrolled by the knob 506 in FIG. 22.

If a maintenance man adjusts the variable powersource to decrease thecurrent flowing through the heating coil 502 in FIG. 25, the volume ofthe expandible material within the temperature-sensitive device 510 willdecrease; and the spring 426 will shift the rod 424 and the housing andactuator of that temperaturesensitive device and the actuator oftemperaturesensitive device 452 to the left. Such a shift will increasethe proportion of warm air introduced into the space or room by theair-mixing control unit of which the wall 400 is a part. As a result,the set point of the temperature-sensitive device 452 will have beenraised. However, if the maintainance man actuates the variable-powersource to increase the current flowing through the heating coil 502 inFIG. 25, the resulting increase in the volume of the expandible materialwithin that temperature-sensitive device will shift the actuator 456 andthe actuator and housing of that temperature-sensitive device to theright. That shift will decrease the proportion of warm air introducedinto the space or room. As a result, the set point of thetemperature-sensitive device 452 will have been lowered.

When the set point of the temperature-sensitive device 452 in FIG..25 isbeing increased, the temperature of the air flowing through the airconduit 404 will increase; and that temperature-sensitive device willtend to shift the rod 424 to a position wherein the proportion of warmair will be reduced. Conversely, as that set point is being decreased,the temperature of the air flowing through the air conduit 404 willdecrease; and that temperature-sensitive device will tend to permit thespring 426 to shift the rod 424 to a position wherein the proportion ofwarm air will be increased. However, because the change in thetemperature of the expandible material within the temperature-sensitivedevice 510 will be so much greater than the change in the temperature ofthe expandible material within the temperature-sensitive device 452, thenew set point of the latter temperature-sensitive device will beessentially controlled by the adjustment of the amount of currentflowing through the heating coil 502.

The embodiments of FIGS. 13 and 18-25 are particularly desirable. Thoseembodiments enable Vernatherm units to be used to control the settingsof the perforated plates or adjustable dampers of air-mixing controlunits, and yet permit the set points of those Vernatherm units to bereadily adjusted even though those Vernatherm units are essentiallyinaccessible from the spaces or rooms where the control levers, knobs,or dials are located.

Whereas the present specification has been described in considerabledetail with respect to several embodiments, it is to be understood thatthis description is merely for the purposes of illustration and thatchanges or variations in the described embodiments may be made bypersons skilled in the art without departing from the scope of theinvention as defined in the ap pended claims.

What I claim is:

l. A system for controlling the temperature within a conditioned spacewhich comprises an air-handling control unit that is connected to saidconditioned space to supply air to said conditioned space, means withinsaid air-handling control unit to create a pressure in said air-handlingcontrol unit which is less than the pressure within said conditionedspace, an elongated sampling passage extending between and incommunication with said conditioned space and said airhandling controlunit so air can flow from said conditioned space through said samplingpassage to said airhandling control unit, a temperature-sensitive devicethat has an adjustable set point, said temperaturesensitive device beinglocated so it is not readily accessible from said conditioned space,said temperaturesensitive device being mounted adjacent the outlet endof said sampling passage so it is close to said airhandling control unitand so the air passing through said sampling passage directly engagessaid temperature-sensitive device, whereby said temperaturesensitivedevice can sense the temperature of said air which flows from saidconditioned space through said sampling passage to said air-handlingcontrol unit, an adjusting means with a settable element which issettable to set said adjustable set point of said temperaturesensitivedevice, said adjusting means being mounted adjacent the inlet end ofsaid sampling passage and thus being mounted so it is remote from saidtemperaturesensitive device, connecting means extending from saidadjusting means to said temperature-sensitive device to enable theadjusting of said settableelement of said adjusting means to adjust saidadjustable set point of said temperature-sensitive device, andmechanical connecting means connecting said temperature-sensitive deviceto said air-handling control unit to enable changes in the temperatureof said air which flows from said conditioned space through saidsampling passage to said air-handling control unitto enable saidtemperature-sensitive device to cause said air-handling control unit toadjust the temperature of the air which it supplies to said conditionedspace, said temperaturesensitive device being mounted adjacent saidairhandling control unit so said mechanical connecting means can beshort in length and thus can have a small mass, the first saidconnecting means being disposed within and extending through saidsampling passage, whereby said sampling passage performs the dualfunctions of conducting air from said conditioned space to saidtemperature-sensitive device and of enclosing and protecting said firstsaid connecting means.

2. A system as claimed in claim 1 wherein said means within said,air-handling control unit is a motor-driven blower, wherein saidsampling passage is connected to the suction side of said motor-drivenblower, wherein said sampling passage is a small cross-section tubelocated within a wall of said conditioned space, and wherein saidmechanical connecting means includes a push-pull linkage.

3. A system as claimed in claim 1 wherein a portion of saidmechanicalconnecting means provides said adjustable set point for saidtemperature-sensitive device, and wherein said portion of saidmechanical connecting means responds to a change in the setting of saidsettable element of said adjusting means to change the effectivedistance between said temperature-sensitive device and said air-handlingcontrol unit and thereby change said adjustable set point for saidtemperaturesensitive device.

4. A system as claimed in claim 1 wherein a portion of said mechanicalconnecting means provides said adjustable set point for saidtemperature-sensitive device,

wherein said portion of said mechanical connecting means includes ahydraulic cylinder and the piston thereof, and wherein said hydrauliccylinder and the piston thereof respond to a change in the setting ofsaid settable element of said adjusting means to change the effectivedistance between said temperature-sensitive device and said air-handlingcontrol unit and thereby change said adjustable set point for saidtemperaturesensitive device.

5. A system as claimed in claim 1 wherein a portion of said mechanicalconnecting means provides said adjustable set point for saidtemperature-sensitive device,

wherein said portion of said mechanical connecting means includes a camthat is movable to vary the effective distance between saidtemperature-sensitive device and said air-handling control unit, whereinan actuator for said cam is movable by said settable element of saidadjusting means, and wherein said cam and actuator therefor respond to achange in the setting of saidsettable element of said adjusting means tochange the effective distance between said temperature-sensitive deviceand said air-handling control unit and thereby change said adjustableset point for said temperaturesensitive device.

1. A system for controlling the temperature within a conditioned spacewhich comprises an air-handling control unit that is connected to saidconditioned space to supply air to said conditioned space, means withinsaid air-handling control unit to create a pressure in said air-handlingcontrol unit which is less than the pressure within said conditionedspace, an elongated sampling passage extending between and incommunication with said conditioned space and said air-handling controlunit so air can flow from said conditioned space through said samplingpassage to said air-handling control unit, a temperature-sensitivedevice that has an adjustable set point, said temperature-sensitivedevice being located so it is not readily accessible from saidconditioned space, said temperature-sensitive device being mountedadjacent the outlet end of said sampling passage so it is close to saidair-handling control unit and so the air passing through said samplingpassage directly engages said temperaturesensitive device, whereby saidtemperature-sensitive device can sense the temperature of said air whichflows from said conditioned space through said sampling passage to saidairhandling control unit, an adjusting means with a settable elementwhich is settable to set said adjustable set point of saidtemperature-sensitive device, said adjusting means being mountedadjacent the inlet end of said sampling passage and thus being mountedso it is remote from said temperature-sensitive device, connecting meansextending from said adjusting means to said temperature-sensitive deviceto enable the adjusting of said settable element of said adjusting meansto adjust said adjustable set point of said temperature-sensitivedevice, and mechanical connecting means connecting saidtemperature-sensitive device to said air-handling control unit to enablechanges in the temperature of said air which flows from said conditionedspace through said sampling passage to said air-handling control unit toenable said temperature-sensitive device to cause said airhandlingcontrol unit to adjust the temperature of the air which it supplies tosaid conditioned space, said temperature-sensitive device being mountedadjacent said air-handling control unit so said mechanical connectingmeans can be short in length and thus can have a small mass, the firstsaid connecting means being disposed within and extending through saidsampling passage, whereby said sampling passage performs the dualfunctions of conducting air from said conditioned space to saidtemperaturesensitive device and of enclosing and protecting said firstsaid connecting means.
 2. A system as claimed in claim 1 wherein saidmeans within said air-handling control unit is a motor-driven blower,wherein said sampling passage is connected to the suction side of saidmotor-driven blower, wherein said sampling passage is a smallcross-section tube located within a wall of said conditioned space, andwherein said mechanical connecting means includes a push-pull linkage.3. A system as claimed in claim 1 wherein a portion of said mechanicalconnecting means provides said Adjustable set point for saidtemperature-sensitive device, and wherein said portion of saidmechanical connecting means responds to a change in the setting of saidsettable element of said adjusting means to change the effectivedistance between said temperature-sensitive device and said air-handlingcontrol unit and thereby change said adjustable set point for saidtemperature-sensitive device.
 4. A system as claimed in claim 1 whereina portion of said mechanical connecting means provides said adjustableset point for said temperature-sensitive device, wherein said portion ofsaid mechanical connecting means includes a hydraulic cylinder and thepiston thereof, and wherein said hydraulic cylinder and the pistonthereof respond to a change in the setting of said settable element ofsaid adjusting means to change the effective distance between saidtemperature-sensitive device and said air-handling control unit andthereby change said adjustable set point for said temperature-sensitivedevice.
 5. A system as claimed in claim 1 wherein a portion of saidmechanical connecting means provides said adjustable set point for saidtemperature-sensitive device, wherein said portion of said mechanicalconnecting means includes a cam that is movable to vary the effectivedistance between said temperature-sensitive device and said air-handlingcontrol unit, wherein an actuator for said cam is movable by saidsettable element of said adjusting means, and wherein said cam andactuator therefor respond to a change in the setting of said settableelement of said adjusting means to change the effective distance betweensaid temperature-sensitive device and said air-handling control unit andthereby change said adjustable set point for said temperature-sensitivedevice.
 6. A system as claimed in claim 1 wherein a portion of saidmechanical connecting means provides said adjustable set point for saidtemperature-sensitive device, wherein said portion of said mechanicalconnecting means includes a second temperature-sensitive device and aheating coil in heat-transferring relation with said secondtemperature-sensitive device, wherein adjusting of said settable elementof said adjusting means will change the value of the current flowing tosaid heat coil, and wherein said heat coil responds to a change in thesetting of said settable element of said adjusting means to change theamount of heat supplied to said second temperature-sensitive device andthereby enable said said second temperature-sensitive device to changethe effective distance between the first said temperature-sensitivedevice and said air-handling control unit with a consequent change insaid adjustable set point for said first said temperature-sensitivedevice.
 7. A system as claimed in claim 1 wherein an expandible elementhelps provide said adjustable set point for said temperature-sensitivedevice, wherein said expandible member is expandible to effect movementof said temperature-sensitive device in one direction relative to saidair-handling control unit, wherein said expandible element iscontractible to effect movement of said temperature-sensitive device inthe opposite direction relative to said air-handling control unit, andwherein said expandible member responds to shifting of said settableelement of said adjusting means in one direction to expand and respondsto shifting of said settable element of said adjusting means in theopposite direction to contract.
 8. A system as claimed in claim 1wherein a second temperature-sensitive element and a heat coil helpprovide said adjustable set point for said temperature-sensitive device,wherein said heating coil is in heat-transferring relation with saidsecond temperature-sensitive device, wherein a change in the currentflowing through said heating coil will enable said secondtemperature-sensitive device to change the effective distance betweenthe first said temperature-sensitive device and said air-handlingcontrol unit and thereby change said adjustAble set point for said firstsaid temperature-sensitive device, and wherein a change in the settingof said settable element of said adjusting means will change the amountof current flowing through said heating coil.